The Self versus Others: Spatial Localization and Timing of Trait Judgments in the mPFC and PCC/Precuneus

Abstract

Simulation theory (ST) states that people understand others through simulation, which counters the probabilistic reasoning view of theory theory (TT). When thinking about traits of a known other, people use self-referential thought. It is unclear which theory—ST or TT—best describes the method by which self-referential thoughts occur. A combination of event-related potential (ERP), event-related spectral perturbation (ERSP), source localization, and hidden semi-Markov model multivariate pattern analysis (HSMM-MVPA) techniques are hypothesized to disentangle self-vs-other information processing and distinguish competing theory of mind theories during a trait judgment task. EEG was recorded for 45 participants (30 females) ages 18-24 (M = 19.4) on resting and task measures, in which participants determined whether character and appearance words matched characteristics of the self and a close and distant other. Data analysis included repeated measures MANOVAs of reaction times, amplitudes and latencies generated from the parietal (PCC/precuneus) P300 and latter components of the frontal (mPFC) and parietal LSW. Time-frequency analysis included evoked and induced power through 100 Hz. ERP data was localized with MNE to verify location and timing assumptions for P300 and LSW. Lastly, HSMM-MVPA provided an alternative look at differences in number and duration of processing stages. The P300/LSW and source localization showed no differences between self, mother, and Fallon, which did not reflect prior BOLD activations. ERP data did not have the specificity to detect changes amid highly variable trials. Differences in self and mother were predicted by induced gamma ERSP, suggesting involvement of gamma in information integration or categorization. HSMM-MVPA models fit TT predictions and showed significant self-other differences in duration of processing and magnitude of peaks. Future research should clarify the role of the mPFC in self-referential thought and its relation to ST and TT with simultaneous fMRI and EEG and populations with impaired self-recognition such as ASD and schizophrenia.